Sheet gripper mechanism



Nov. 7, 1961 Filed May 6 1959 H. M. TAYLOR ET AL SHEET GRIPPER MECHANISM2 Sheets-Sheet 1 Nov. 7, 1961 H; M. TAYLOR ET AL 3,007,408

SHEET GRIPPER MECHANISM Filed may 6, 1959 2 Sheets-Sheet 2 In ven tor!WMWW 757 M W 4 20mm My Whit;

A ttorney:

United States Patent This invention relates to sheet gripper mechanismsemployed in rotary sheet handling machines and particularly sheetprinting machines: for convenience, reference will be made only torotary printing machines in what follows.

Such machines employ one or more impressioncylinders equipped with sheetgrippers which takehold of a sheet and carry it around with the cylinderduring which time the sheet receives a printing impression: such acylinder has strained about its periphery an impression sheet which canbe of various materials selected .to provide a support to the papersheet during the impression: such impression sheets are in the form ofblankets and are commonly referred to as such and this term willhereinafter be employed.

The blanket is strained about the cylinder by attaching its ends tomechanisms which are necessarily housed in a recess in the body of thecylinder: the gripper mechanism is also housed in a recess in the body:the blanket must extend to support the paper sheet to a point close toits leading end where it is engaged by the gripper fingers of thegripper mechanism: in the result therefore, the gripper operatingmechanism is positioned close to and in front of the straining mechanismfor at least the leading end of the impression sheet.

The blanket has to be replaced from time to time and to do this it isnecessary with the known constructions to dismantle more or less of thegripper mechanism to enable the leading end vof the blanket to beintroduced into its recess, there to be engaged by the strainingmechanism. This is a time-consuming operation and results in disturbingthe somewhat precise settings of the various parts of the grippermechanism.

It is the main purpose of this invention to provide an arrangement whichwill overcome the disadvantages referred to.

Broadly stated, the present invention consists as to one feature informing the gripper mechanism as a unit which is detachably mounted inposition so that it can be removed to expose the straining mechanism andthen replaced without the setting of its parts having been disturbed.

It is necessary to provide some form of slip connection between thegripper mechanism on the gripper unit and the operating mechanism forthe various grippers of the unit: the operating mechanism can comprise ashaft mounted for oscillation in the cylinder and having a series ofarms one for each of the gripper fingers of the unit: these arms areprovided with tappets to engage the gripper fingers, the engagementproviding the slip connections referred to.

It is preferred to bias the gripper fingers individually to their closedor gripping position for such a biasing arrangement has been found toprovide a smoother action than that given by relying on single bias forall of the grippers.

A further feature of the invention relates to the formation of the partof the cylinder against which the gripper fingers press the sheet whenthe fingers are in their sheet gripping positions: this surface,hereinafter termed the seating surface should be at the level of theunder face of the sheet: in practice, to obtain good printing resultsthe blanket is selected as to its thickness to suit the 3,007,408Patented Nov, 7, 1961 ice thickness and quality of the paper to beprinted.- When therefore a seating surface in a fixed position is used,the position can only be a compromise for blankets of dilferentthickness. I

. According to a further feature of this invention, the seating surfacefor the gripper fingers is formed on components which are supported bythe cy-linder for adjustment as to its setting radially of the cylinder:in this way the height of the seating surfaces for the gripper fingerscan be set to a fine limit to suit the thickness of the blanket to beused in any particular printing operation. 7

The two features of the invention can be combined and in this case thegripper seating component would be mounted on theremovable gripper unit.v

A construction embodying the two features is shown in the accompanyingdrawings, FIGURE 1 of. which is a transverse cross section showing thegripper unit in position in chain dotted linesand. removed in full linesand FIGURE 2 of which is a side-elevation to a smaller scale of thecylinder in the regionof its two ends.

Referring to the drawings, an impression cylinder is indicated at 1,this cylinder having recesses 2, 3 accommodating any usual form ofblanket straining mechanism for tensioning the blanket about the surfaceOlf the cylinder 1: in the particular arrangement shown, this mechanismcomprises two bars 4, 5 to which the ends of the blanket, indicated atB, are secured, the two bars being turned to strain the blanket andbeing held in position as by a pawl and ratchet device indicated at Sofor the bar5..

The recess 2 is-enlarged at 6 to receive a sheet gripper mechanism unitcomprising a series 7 of fingers 7 mounted to turn on a spindle 8. Thespindle is secured in a frame or support 9 which is clamped by'bolts 10to a seating 11 presented by the recess 2, the f ame 9 having slots 12to enable the frame to be slippedinto position under the heads of the,bolts 10 by which the gripper mechanism unit is normally but detachablyfixed to the cylinder 1. Both the blanket strainingbar 4 and the sheetgripper mechanism unit arev housed within the recess 2, 6 which extendsinwardly from the periphery of the cylinder 1 towards the cylinder axis;

The fingers 7 cooperate with a seating surface 13 formed on the frame 9and the fingers are individually biased by springs 14- to their closedposition, i.e., against the seating surface 13, the springs reactingagainst brackets 14a secured to the fixed spindle 8.

The fingers have extensions 15 fitted with followers 16 having slipconnection engagement with the heads of individually adjustable tappets17 on arms 18 on an operating spindle 19 mounted to oscillate inbearings in the recess 6 in the cylinder. This spindle 19 is arranged tobe oscillated in any usual way as the cylinder rotates: in thearrangement shown, the spindle19 is provided with an arm 19a carrying aroller 19b engaging an operating cam track (not shown) which operates torock the spindle against the action of return springs 19c acting on thearms 18. In this oscillation, the tappets 17 contact the grippers toopen them against the action of the various springs 14 (at which time a.sheet is presented to the grippers) and then allow the fingers to beclosed by the action of their springs (at which time the sheets aregripped between the fingers 7 and the seating 13).

By releasing the various securing bolts 10, the frame 9 which carriesthe gripper assembly described can be removed as a unit as is indicatedin FIGURE 1, the followers 16 parting from, i.e., slipping from underthe tappets 17. The blanket tensioning bar 4 is now fully exposed toenable access to be gained easily to it, for a blanket renewingoperation: at the end of that operation the gripper assembly unit isreplaced and its parts will have exactly the same setting as theypreviously had with respect to the operating tappets 17 and the seating13.

As is also shown in the drawing, provision is made to adjust the radialsetting of the seating 13: this is elfected by disposing under the loweredge of the frame 9 the bevelled ends 20 of slides 21 which can be slidby adjusting studs 22: by slackening the bolts and turning the studs 22,the frame 9 can be adjusted radially within fine limits to enable thesetting of the seating 13 to be adjustai to suit any particular blanketthickness: the slides 21 are then locked by clamping bolts 23 in a bar24 which is secured to the cylinder and is notched at intervals toreceive the various slides 21.

We claim:

1. In a rotary sheet printing machine, an impression cylinder formedwith a recess extending inwardly from the periphery of the cylindertoward the axis thereof; means mounted on said cylinder within saidrecess for straining an impression blanket about the cylinder periphery;a sheet gripper mechanism unit comprising a support, a seating on saidsupport and gripper finger means mounted on said support for movementinto and out of sheetgr-ipping position relative to said seating;releasable securing means within said recess detachably fixing saidsupport to said cylinder for mounting said sheet gripper mechanism unitwithin said recess adjacent said blanket straining means and formovement together with said cylinder without movement of said unitsupport relative to said cylinder, releasing of said securing meansenabling com plete removal of said sheet gripper mechanism unit, therebyto render said blanket straining means accessible from outside saidcylinder; and means for operating said gripper finger means duringrotation of said cylinder COHL prising a shaft mounted on said cylinderand extending in said recess, and normally engaged slip meansoperatively connecting said shaft to said gripper finger means andincluding cooperable parts separable from each other upon releasing ofsaid securing means and removal of said sheet gripper mechanism unitfrom said recess.

2. In a rotary sheet printing machine, an impression cylinder formedwith a recess extending inwardly from the periphery of the cylindertowards the axis thereof; means mounted on said cylinder within saidrecess for straining an impression blanket about the cylinder periphery;a sheet gripper mechanism unit comprising a support, a seating on saidsupport and gripper finger means mounted on said support for movementinto and out of sheetgripping position relative to said seating;releasable securing means within said recess detachably fixing saidsupport to said cylinder for mounting said sheet gripper mechanism unitwithin said recess adjacent said blanket straining means and formovement together with said cylinder without movement of said unitsupport relative to said cylinder, releasing of said securing meansenabling complete removal of said sheet gripper mechanism unit, therebyto render said blanket straining means accessible from outside saidcylinder; and means for operating said gripper finger means duringrotation of said cylinder comprising a shaft mounted on said cylinderand extending in said recess, and means on said shaft within said recesscontactable with said gripper finger means when said sheet grippermechanism unit is fixed in said recess but being separable from saidfinger means upon releasing of said securing means and removal of saidunit from said recess.

3. In a rotary sheet printing machine, an impression cylinder formedwith a recess extending inwardly from the periphery of the cylindertowards the axis thereof; means mounted on said cylinder within saidrecess for straining an impression blanket about the cylinder periphery;a sheet gripper mechanism unit comprising a support, a seating on saidsupport and gripper finger means mounted on said support for movementinto and out of sheet-gripping position relative to said seating;releasable securing means within said recess detachably fixing saidsupport to said cylinder for mounting said sheet gripper mechanism unitwithin said recess adjacent said blanket straining means and formovement together with said cylinder without movement of said unitsupport relative to said cylinder, releasing of said securing meansenabling complete removal of said sheet gripper mechanism unit, therebyto render said blanket straining means accessible from outside saidcylinder; means for operating said gripper finger means during rotationof said cylinder; and setting means for varying the position of saidseating radially with respect to said cylinder.

4. Construction according to claim 3 in which said setting meanscomprises a member mounted on said cylinder for sliding within saidrecess and engaging said unit support.

References Cited in the file of this patent UNITED STATES PATENTS640,798 North Jan. 9, 1900 1,208,731 Blaine Dec. 19, 1916 1,686,065Blaine Oct. 2, 1928 1,916,454 Wohbrabe July 4, 1933 2,436,765 Davidsonet al Feb. 24, 1948

